Diaphragm piston pump



July 25, 1961 F. W. PLEUGER ETAL DIAPHRAGM PISTON PUMP Filed May 27, 1958 ATTORNEYS United States Patent 2,993,446 DIAPHRAGM PISTON PUMP Friedrich Wilhelm Pleuger, Juthornstrasse 8, Hamburg,

Germany, and Heinz Gohring, Hamburg-Waudsbek,

Germany; said Gohring assignor to said Pleuger Filed May 27, 1958, Ser. No. 738,213 Claims priority, application Germany June 1, 1957 4 Claims. (Cl. 103-44) This invention relates to pumps and is especially concerned with submersible deep well pumps of the type wherein a flexible pumping diaphragm divides a pumping chamber from a working chamber filled with hydraulic fluid and wherein the diaphragm is flexed by means of a piston which acts upon the fluid in the working chamber.

In pumps of the character described it is important that the volume of fluid in the working chamber be constantly maintained. For instance, if leakage from the working chamber occurs, such loss must be compensated for. Heretofore, it has been known in the art to effect this compensation by feeding additional hydraulic fluid to the working chamber through suitable check valves during the suction stroke of the piston. However, this procedure has involved certain disadvantages. For instance, an increase of the normal volume of the hydraulic fluid in the working chamber due, for example, to heat or to uncontrolled operation of the check valves, could, heretofore, be reduced only through losses due to seepage or leakage, Under such conditions the diaphragm may have to flex excessively over relatively long periods of operation which undesirably increases the stains imposed upon it. In extreme cases, this may well result in permanent damage to the diaphragm and may even involve a degree of deflection which is sufiicient to block the flow of the liquid through the pumping chamber of the pump.

The principal object of the present invention is to avoid the difliculties and disadvantages just referred to by providing improved means for equalizing the volume of the hydraulic liquid in pumps of the character de scribed and to accomplish this promptly and reliably as well as to constantly relate the equalization directly to the working position of the diaphragm.

How the foregoing objects together with such other objects as may appear hereinafter or are incident to our invention are attained is illustrated in preferred form in the accompanying drawings wherein:

The figure is a somewhat schematic axial section through a submersible deep well pump.

In the embodiment illustrated in the drawing a pump casing 1 contains a cylindrical body 2. A head piece 3 connects the body to the discharge pipe 4. The head piece is secured to the body 2 in any desired manner (not shown) and a suitable gland and packing are provided for fluid tightness as shown.

In a crossbore in the body 2 an eccentric shaft 7 is mounted in ball bearings 5 and 6 which shaft is driven through bevel gears 8 and 9 by shaft 10 of an electric motor 32, likewise enclosed within the pump casing 1.

An eccentric shaft 7 drives the pumping piston 13 through a tappet 12 against the effect of a spring 11. Pumping piston 13 transmits its movements through bydraulic fluid to the pumping diaphragm 14 which latter is clamped between the body 2 and the headpiece 3. The diaphragm 14 separates the pumping chamber '15 from the chambers 16 and 17 which are interconnected by passages 18, the chambers 16 and 17 and the passages 18 being filled with hydraulic fluid. The diaphragm 14 protects the working parts of the pump and the pump drive from contamination by the liquid being pumped. The pumping chamber is connected with the discharge pipe 4 through a bore or passageway 19 2,993,446 Patented July 25, 1961 ice under the control of foot valve 20 which prevents back flow. The liquid being pumped enters through a strainer 21 and passes through the suction passage 22 under the control of suction valve 23 which latter is a check valve adapted to close on the discharge stroke of the diaphragm.

Chamber 24 serves as a reservoir and equalization tank for the hydraulic fluid, all of the parts which drive the pumping piston 13 being arranged to operate in this reservoir. The equalizing flexible membranes 25 transfer the surrounding pressure to the hydraulic fluid stored in the reservoir.

Two lines, namely, 26 and 28, are provided to connect the hydraulic fluid reservoir 24 with the working chamber. These lines terminate at their upper ends in ports which are controlled by a suitable valve 30 which in the present instance takes the form of a piston or slide valve which valve is coupled by a stem 31 to the pumping diaphragm 14 although it will be understood that any suitable interconnecting means may be employed for this purpose such, for example, as a compensating linkage.

A plurality of lines 26 and 28 may be employed if desired, although only two are illustrated in the present embodiment. One line, i.e., the line 26 in the present embodiment is provided with a check valve 27 which permits flow only from the reservoir into the work chamber. In the other line, a check valve 29 permits flow only from the working chamber into the reservoir.

The terminal ports of the two lines 26 and 28 are so constructed and arranged in the path of the control piston 30 that one end of the piston will uncover the port of line 26 and allows hydraulic fluid to flow past the check valve 27 into the working chamber whereas the other end is arranged to uncover the port of line 28 and permit hydraulic fluid to flow out of the working chamber past the check valve 29 into the reservoir 24.

When the pump is in operation the eccentric shaft 7 drives the tappet 12 against the piston 13 forcing this piston against the compression of the spring 11 and the hydraulic fluid contained in the chambers 16 and 17 (constituting the working chamber) thereby forcing the fluid against the pumping diaphragm 14 to flex the latter in a direction away from its medial position between the chambers 15 and 16. Since the control piston valve 30 is coupled to the diaphragm 14, it will be obvious that the valve will move with the diaphragm. However, under normal conditions of operation the valve will not uncover the ports of lines 26 and 28 and will keep the working chamber isolated from the hydraulic reservoir.

Any reduction in the volume of the hydraulic fluid in the chamber and passages between the piston and the diaphragm 14, due to leakage losses through the tappet and piston clearances, will serve to displace the diaphragm from its medial position and cause flec-tion thereof to a point further down into the working chamber 16. Since the control piston 30 will be simultaneously displaced to the same degree, it will uncover the port of line 26 and make it possible for the hydraulic fluid contained in the reservoir 24 which is subject to the external pressure through the membranes 25 to open the check valve 27 and permit entry of the hydraulic fluid from the reservoir into the working chamber to compensate for the reduction of the volume thereof due to the leakage. In like manner, the control piston 30 will uncover the port of line 28 as soon as the diaphragm 14 shifts its medial position and amplitude of flection toward the pumping chamber 15 due to the increase of the volume of hydraulic fluid in the working chamber 16-17. Undesired overfilling of the working chamber is then compensated for by passage of said excessive hydraulic fluid past the check valve 29 through the passage 28 into the reservoir 24.

3 Adjustment of the hydraulic fluid volume in the working chamber occurs instantly and constantly as soon as the diaphragm 14 shifts its amplitude of flection upward or downward sufliciently far to bring the control valve or piston 30' into a position in which it Will uncover one or the other of the ports 26 or 28. Likewise; the communication between working chamber 16-17 on the one hand and the hydraulic reservoir 24 on the other hand is immediately shut off when the diaphragm returns to its normal medial position after the hydraulic fluid volume in the working chamber has been suitably adjusted. in this way, any positive or negative variation in the volume of the hydraulic fluid is compensated for without delay which proteets'the diaphragm against intolerable flection and excessive strain over-any considerable period of time. At the same time the arrangement is such as to prevent the diaphragm from shifting its range of fiection too far into. the pumping chamber 15 and thus blocking the suction and discharge lines of the pump. 7

We should like to add that the controlling device for the hydraulic fluid can be operated by the diaphragm either directly or indirectly as, for example, by hydraulic, electrical or other means just so long as the equalization process is initiated and terminated under the direct control of the diaphragm itself. The embodiment illustrated is a preferred arrangement because of its simplicity and effectiveness.

We claim:

1. A submersible, deep-well pump comprising a housing enclosing a pumping chamber having an inlet and an outlet for the well fluid to be pumped, a discharge pipe connected to the pumping chamber, a constant volume working chamber, a flexible pumping diaphragm separating said chambers, said Working chamber being filled with hydraulic operating fluid, a reservoir of hydraulic operating fluid, said reservoir having in an external wall thereof a flexible membrane adapted to respond to the pressures in the reservoir and. in the well,

a pumping piston with an operating face forming a portion of the Wall of the working chamber, a motor for reciprocating the piston, a hydraulic fluid line connecting the reservoir and the working chamber and adapted to deliver fluid from the reservoir to the working chamber, a hydraulic fluid line connecting the reservoir and the working chamber and adapted to deliver fluid from the Working chamber to the reservoir, valve means closing both of said fluid lines during normal operation of the pump, and means responsive to the physical position of the diaphragm for actuating said valve means to effect opening of the line which delivers to the working chamber when the diaphragm is insufliciently flexed toward the pumping chamber and to effect opening of the line which delivers to the reservoir when the diaphragm is flexed too greatly toward the pumping chamber.

2. A pump according to ciaim 1' wherein the valve means controlled by the diaphragm is avalve coupled directly to the diaphragm.

3. A pump according to claim 1 wherein a check valve is provided in each of the fluid connecting lines,

4. A pump according to claim I wherein the valve' means controlled by the diaphragm includes a slide valve and an actuating rod directly interconnecting the valve and the diaphragm.

References Cited in the file of this patent UNITED STATES PATENTS 1,650,377 Nixon Nov. 22, 1927 1,853,147 Reynolds Apr. 12, 1932 2,126,310 Clench Aug. 9, 1938 2,478,568 Coe Aug. 9, 1949 2,578,746 Schenger et al. Dec. 18, I951 2,634,687 Smith Apr. 14, 1953 2,703,055 Veth et al. Mar. 1, 1955 2,861,518 Pleuger Nov. 25, 1958 2,919,650 Wiggermann Jan. 5, 1960 

